So it seems that you were not considered separated from service and your loan became a deemed distribution. This means that the loan has not been satisfied and you are still obligated to make payments on the loan. However, payments that you make become after-tax basis in the 401(k), so you won't pay taxes again on this money.
Because the distribution event (the deemed distribution) occurred after December 30, 2020 as evidenced by it being reported on a 2021 Form 1099-R, it's not a Coronavirus-Related Distribution that would be eligible for splitting the income in equal parts over three years. It could only be a CRD if reported on a 2020 Form 1099-R. You owe income tax and a 10% early distribution penalty on the entire amount on your 2021 tax return.
